The properties of foam and bubbles in carbonated drinks are one of the major factors that determine the taste of carbonated drinks. For this reason, various methods have been proposed to create a fine foam when drinking, to make the foam created last longer, and further to enhance the texture and taste. Examples thereof include a method in which a fine foam is caused to form by adding saponin, a foaming agent, thereby improving the foam retention (Patent Literature 1), and methods in which a fine foam is caused to form and/or the foam retention is improved by adding a protein, a degraded protein product, an emulsifier, a degraded starch product, a tea extract, or the like (Patent Literatures 2 to 6).
On the other hand, various phosphates have been used in carbonated drinks and non-carbonated drinks to serve as acidifier, chelating agent, anti-fade agent, antibacterial agent, and the like. For example, Patent Literature 7 discloses a non-carbonated diluted juice drink product which contains (i) a specific preservative, (ii) specific polyphosphate (sodium hexametaphosphates, and the like), (iii) added water having a hardness of 0 to 60 ppm, and which has a pH value of 2.5 to 4.5 as a final product and can be stored at environmental temperature for at least 10 days without substantial bacterial growth; Patent Literature 8 discloses a non-carbonated diluted juice drink product which contains (i) a specific antiseptics, (ii) a specific sodium polyphosphate, (iii) added water having a hardness of 61 to 220 ppm, and which has a pH value of 2.5 to 4.5 as a final product and can be stored at environmental temperature for at least 28 days without substantial bacterial growth. Further, Patent Literature 9 describes a carbonated drink with a green tea powder which contains the green tea powder, an antioxidant and 0.2 g/100 g (=2000 ppm) of a polymeric phosphate with carbon dioxide gas injected therein, is free of color fading or changing over an extended period of time, and maintains the green tea taste and flavor; Patent Literature 10 describes an orange juice having a low gas pressure containing 0.6 g/2.3 L (≈260 ppm) of polyphosphate and 350 mL of carbonated water. Furthermore, the above Patent Literature 5 discloses that the polymeric phosphate added to the carbonated drink is capable of achieving the improvement of taste, i.e., imparting mildness, but fails to exhibit the effective in creating a fine foam or improving the foam retention.
Still furthermore, Patent Literature 11 describes an additive for carbonated drinks which comprises spilanthol or a spilanthol-containing plant extract or plant essential oil used to solve the problems of the reduced carbonate sensation (stimulation, cooling sensation, etc.) caused by rapid evaporation of carbon dioxide gas after opening and of thus quickly lost function and palatability demanded for a beverage after opening.